In the field of automobile manufacturing, more and more components, including various structural components, are made of plastic materials in order to reduce the overall weight and thus save fuel. The so-called structural components refer to those components which provide required stiffness and strength for vehicle body and usually bear or support other components.
Although plastic materials are lighter than metals, their strengths are generally lower than those of metals. Therefore, plastic materials are usually used to manufacture the portions of structural components, which don't require high strength, while the areas under higher stress still need to be strengthened by metal parts.
For example, for structural components of motor vehicle parts, particularly closing parts (usually their inner panels), the areas under higher stress include the areas where hinges are mounted.
For tailgates which need to be supported by power assisting devices, the areas under higher stress also include columns on which hydraulic levels or air spring struts, etc. are installed. In prior art, these areas are usually strengthened by metal parts to meet the design requirements for stress.
However, metal parts are heavy and expensive, and their processing relates to such complicated processes of high cost as punching, overmolding which is necessary for binding the metal parts with plastic portions, etc.